Billy Sheahan Photography Class 102 – Choosing a DSLR Camera and Lenses

Billy Sheahan Photography Class 102

Choosing a DSLR (Digital Single Lens Reflex) Camera and Lenses

This is part two in a series of photography discussions to help you make the most of your photographs. If you haven’t read Class 101, it will probably be easier to follow Class 102 if you do so first. And there is a Class 103 called, Finding Your Style, here.

DSLR Basics

Since camera technology evolves constantly, this will be a very broad overview – just the basics to help you determine what kind of photographs and more recently motion images you intend to make with your DSLR camera. In fact, that’s the most important first question I ask people when they come to me seeking advice on what DSLR camera they should buy.

What are you going to take pictures of?

Billy in Paris (photo by Morgan Hughes) ©2005

Billy in Paris (photo by Morgan Hughes) ©2005


Will you be making photographs of people, perhaps of models or family portraits? Will you be shooting anything fast moving such as sports or dancing? Documentary photography? Will you be shooting buildings or architecture? Maybe you’ll be shooting a bit of all of these things, but it’s good to know the answer to those questions before you consider what you’ll need to start with as far as cameras and lenses go.

Once you answer the What kind of photographer am I? question, you can more accurately determine what camera tools you’ll need to achieve your vision. The camera doesn’t make the photographer, the photographer makes the photographer.

It’s easy to fall into the thinking that I could make better photographs if only I had a better camera. That statement is probably more false than true. Master photographers were making timeless images with cameras you might find at a garage sale today… well… maybe a garage sale in a well to do neighborhood, but you get my point.

Digital cameras have opened up new ways to make images, but nothing replaces practice and experience when learning how to tell a story with a single image. To be a good or great photographer, it’s much more about composing and envisioning an idea or capturing something wonderful in your subject, so much more than the camera you have in your hands.

Of course, with that being said, you should know your tools as well. Todays DSLRs are phenomenal technical tools. They can also be very complex and intimidating to new photogs. Let’s break down the crucial information into two very basic areas, the camera sensor and the lenses you may choose to use.

The camera sensor or chip:

Digital cameras use a sensor, sometimes called a chip, in place of film to expose a photograph electronically rather then light sensitive chemicals on a piece of film. The principles are the same with both. The camera body and lens determine how much light falls on the sensor to make the image.

Most DSLR cameras have one of two sizes of chips. The first is sometimes called a full-size sensor which is comparable in size to a 35mm still frame (36mm x 24mm). The second sensor size is a little smaller and is sometimes referred to as APS-C size (22.3mm x 14.9mm). Full sized chips are more expensive than APS sensors and are usually only found on professional level cameras. This may change as the technology evolves, but currently if you purchase a DSLR camera body with a full sized sensor, you will probably pay at least $1000 more for it. Sometimes a lot more than that depending on the features of the camera.

APS sensors are perfectly fine for most people who don’t make their living as professional photographers. So what’s the difference?

A larger sensor can usually (but not always) make a decent image in lower light than a smaller sensor. A larger sensor will also usually have a greater amount of pixels on it. However, as I mentioned before, technology is constantly changing and a smaller sensor on todays cameras is probably more than comparable to a larger sensor in a camera made five years ago.

In addition, a greater number of pixels does not always mean a better photograph either. A lot goes into cramming millions of pixels on a chip the size of a postage stamp. Some manufacturers use techniques that are better than others. The number of pixels does have a lot to do with how large a photograph can be blown up without getting soft and muddy, but it’s not the defining factor in how sharp any given image is.

A much more important factor in the technical quality of the image are the lenses you choose to use.

DSLR Lenses – Full Size vs DX:

In my opinion, for beginning photographers, a good lens is going to have more to do with how your photograph looks than sensor size or pixel count. There are many factors to consider when choosing your lenses.

Billy and photog friends at Native American Ruins in Santa Fe, New Mexico (photo by Sarah Cramer) ©2008

Billy and photog friends at Native American Ruins in Santa Fe, New Mexico (photo by Sarah Cramer) ©2008


Since we just discussed sensor size above, let’s start there with how that relates to lenses. Just as DSLR camera manufacturers make two main sizes of camera sensors, full size and APS, they also make two types of lenses designed to focus the image exactly onto the area of those two sensor sizes. They are sometimes referred to as full-sized lenses for large full-sized sensors and DX lenses for the smaller APS sensors.

The main rule to be aware of is that while you can use a full-sized lens on a camera with a smaller APS sized sensor, you can’t go the other way. You cannot use a DX lens (a lens designed to work with an smaller APS sensor) on a camera with a full-sized sensor.

Why not? If you recall the difference in chip surface sizes from the section above, a full sized lens “projects” a 36mm x 24mm image from outside the camera, through the lens, onto the sensor, perfectly matching the size of the sensor. A DX lens “projects” a smaller 22.3mm x 14.9mm image from outside the camera, through the lens, onto the sensor. If you put a DX lens on a camera with a full frame sensor, the “projected” image will not fill the area of the full-sized sensor. The image area from the DX lens will be smaller than the full size sensor surface area.

An analogy that might help clarify this point is to imagine two flat screen televisions. One is a 50 inch screen an another is a 36 inch screen. If you could peel off the screen image area of the 36 inch television and place it on the 50 inch television, you will not fill the screen area of the 50 inch television. There will be blank space at the top, bottom and both sides of the image because the screen area of a 36 inch television image is much smaller than a 50 inch screen area. That is similar to putting a DX lens on a full size camera sensor. The image area will not fill up the entire surface of the sensor.

Why does this even matter? Why not simply purchase DX lenses for APS sized sensor cameras and full size lenses for full size sensor cameras? The answer is, of course you can simply do that. One thing to be aware of however is that in a few years you may choose to upgrade your smaller sensor camera to a full size sensor camera. As sensor technology evolves and gets less expensive in the coming years, you may be able to purchase a full-sized sensor camera for the same price as you paid for your APS sensor camera.

If you purchase DX lenses now, you won’t be able to use them on a full frame sized sensor camera later. Buying full-sized lenses now, future proofs your purchase as long as you stay with the same brand of DSLR camera. Digital cameras come and go, but good lenses can last decades if they are well cared for. One of my favorite lenses is 32 years old. I’d bet that I won’t be using the same DSLR camera in ten years, let alone 30. You don’t want to have to upgrade your lenses when you upgrade your camera.

The second thing to be aware of is that if you do choose to purchase a smaller sensor APS camera and use full size lenses with it, you will have to do a bit of math in converting the focal length of a full size lens to the size of your APS sensor. You will have to multiply the focal length of your full size lens by approximately 1.6 magnification to get the focal length equivalent on your APS camera.

In plain English, a 50mm full frame sized lens becomes an 80mm lens. A 200mm full frame sized lens becomes a 320mm lens. This is because the full frame sized lens is “projecting” an image larger than the size of an APS chip. It’s projecting a 36mm x 24mm image onto a 22.3mm x 14.9mm area. Some of that extra image area is going to be cropped off. It’s not a bad thing. You’re not losing any resolution or anything like that. And what you see in your camera viewfinder will be exactly the framing that is captured by the camera.

In fact, you really don’t even need to be aware of the 1.6 magnification issue when using a full frame sized lens on an APS camera. What you see in the viewfinder is what you will get. Only know that the same lens on a full frame sized sensor camera will be a little wider in focal length.

Now, none of this matters if you decide to purchase a full frame sensor camera. You’ll buy full frame lenses that match your full frame sensor camera. And I congratulate you for having a lot of money.

But for the beginning photographer, the extra cost of a full frame camera is… well… most likely impossible. Better to start with a less expensive APS DSLR camera body, which, just like computers, are likely to become obsolete in the rush of technology in a few years time. By pairing an APS DSLR with good full frame sized lenses, your lens purchases will retain their value and usefulness much longer than the ever evolving digital camera technology. And cheating the technology depreciation curve is always a good thing when you can do it.

Applying Your Newfound Sensor and Lens Knowledge:

Let’s now take all of the complex information above and turn it into something practical by going back to the first question. What kind of photographer are you going to be?

Will you be making images of people, relatively close up? Will you be shooting something where you need to freeze the action? Will you be far away from that action? Will you be shooting in indoor low light situations or outdoors? Will you need to fit large building exteriors into your frame?

In the Billy Sheahan Photography 101 Class, which hopefully you’ve read, I discussed how you use aperture settings on your lens to vary depth of field along with shutter speeds to determine how those choices can turn your vision of a photograph from adequate to great.

The bottom line is that you’re going to want to purchase the fastest lenses you can afford. Let’s review what a fast lens is. A fast lens is one that allows more light to pass through the glass and onto your sensor than a slower lens. The term faster comes from the amount of time the shutter has to be open to make a proper exposure. You can use a faster shutter speed and still get the required amount of light to your camera sensor if you have a fast lens. The glass elements in the lens are always going to reduce the amount of light coming into the lens as it focuses the image on the sensor. A faster lens is just going to reduce the light less. That lens glass in a fast lens is higher in quality than a slower lens and therefore more expensive. In other words, the faster the lens, the more expensive it’s going to be.

The speed of a lens can be determined by the f-stop number rating on the lens. Lower is faster. An f2.0 lens is faster than an f4.0 lens. A very fast lens can have an aperture opening as low is f1.4 or even lower in some cases.

Some of the more inexpensive zoom lenses list two f-stop numbers on them, such as f-3.5-5.6. This means when the lens is zoomed all the way out it’s aperture is f3.5, but when it’s zoomed in to its most telephoto setting, it slows down to f5.6 because of the way the glass moves inside the lens to magnify the image. A higher quality and more expensive zoom lens will have a consistent maximum wide open aperture setting all the way through its range of zoom, usually f2.8 or faster.

If you buy a DSLR camera with what is called a kit package, you may get some additional accessories and a lens, all in one box. It’s convenient to get everything as a single package, but to keep the price low, the camera manufacturers usually include a fairly slow zoom lens as part of it. For example a kit may come with an 18-135mm zoom lens with an aperture of f3.5-5.6. This is a very slow lens especially when zoomed in all the way at f5.6.

I always recommend buying the camera body and lenses separately. That way you can choose the exact lens you want (and usually a much faster lens) for the type of photography you’re going to be doing for close to the same price if you do little research. By choosing your lens separately, you won’t find out later the hard way how much more light you need to make a good exposure with a slow kit lens.

Billy in Santa Fe, New Mexico (photo by Sarah Cramer) ©2008

Billy in Santa Fe, New Mexico (photo by Sarah Cramer) ©2008


So how do you get around the high price of a fast lens? There is actually a simple answer. Purchase one or two fast prime (non-zoom) lenses instead of a zoom lens to get you started. Zoom lenses are always going to be more expensive than prime lenses. You can probably find a fairly good quality new Canon or Nikon 50mm f1.8 lens for about $100. It’s not a perfect lens, just a good lens, but it’s a great value for the money. And more importantly, it’s incredibly fast. The kind of lens you can shoot with in birthday candle light. You’d never be able to do that with an f5.6 lens.

If you’re asking, but I think I need a zoom lens so I can easily change my focal length, my standard response is always zoom with your feet! In other words, it you want your composition to be tighter, move closer to your subject. If you want to be wider, move away. Zoom lenses are wonderful, but I’m trying to save you some money here.

If you’re shooting sports and you need to be closer to the action, buy a fast prime f2.8 or faster telephoto lens of 200 or 300mm in length. In sports especially, you are going to want to freeze the action which means a much higher shutter speed, requiring a faster lens to compensate for the shorter time frame that light is entering the camera and still make a proper exposure.

If you’re shooting subject matter that you can get fairly close to, that 50mm f1.8 lens or even an f2.0 lens will be perfect for you to start with. You can shoot in very low light if necessary and by shooting wide open at f1.4, you’ll get a beautiful bokeh (BOH-kah) which is a photographic term used to describe the out of focus part of your image. In other words, your subject is in sharp focus but the background and anything in the foreground are out of focus. This phenomenon is also referred to as a very shallow depth of field. This really makes your subject stand out from the background and can convey an increased amount of emotion in your photography, drawing your viewers eye to your subject without being distracted by details in the background.

You can certainly do the same thing with shallow depth of field using a longer telephoto lens of 200mm or greater even if it happens to be a slower lens using an aperture of f5.6 or f8, but you’ll have to be much further away from your subject to get the proper framing you may be envisioning.

If you are planning to shoot architecture or news or documentary work, a wider lens may be just what you’re looking for. I have traveled abroad with only one camera body and one lens, a 24mm lens and made great images that really show off the architecture or landscape of wherever I happen to be. Wide lenses are also great for news photojournalism or documentary work in that they are able to convey the environment around your subject even when you are fairly close to your subject. Just make sure if your subject is a human you don’t get too close with a wide angle lens. Being too close can distort their facial features in a funhouse mirror kind of way and is rarely flattering. Unless that’s what you’re after!

A 24mm lens allows you to make images that take in more area in your frame than a 50mm lens, which is sometimes referred to as a normal lens. In other words, the viewing angle of a 50mm lens is what you would normally see with your eyes. A wider 24mm lens is sometimes called a short lens and can capture a much wider angle of view in your frame than your eyes normally can take in from the same distance.

A telephoto lens of 150mm or more is sometimes referred to as a long lens and gives you a composition much closer than you can see with your eyes. And in the middle of the normal and telephoto focal length lenses is what is sometimes referred to as a portrait lens. A lens of around 80-110mm is usually called a portrait lens. It’s long enough to help give you more of that out of focus bokeh to make your subject pop, without you having to be so far away from your subject that you can’t communicate with them without raising your voice!

Now all of these focal lengths I’ve listed above are full size lenses being used with full size chip cameras. If you go against my recommendation and purchase DX lenses designed to be used with your APS sensor cameras, all of those 24mm, 50mm and 200mm numbers I’ve been talking about will remain true.

However, if you’re planning to follow my advice and future proof your lens purchases by purchasing full frame lenses even if your camera body uses the small APS sensor chip, you’ll have to do a little math to make my numbers work. I know, I know… everything is a compromise.

Since you’ll have to take into account the 1.6x focal magnification factor when using a full frame lens on an APS sensor camera, the math goes something like this:

In order to get the 50mm normal focal length on your APS sensor sized camera, you’ll have to use a 30-35mm full frame sized lens, which when multiplied by 1.6, gets you very near to a 50mm normal focal length equivalent on a standard 35mm film camera or full frame DSLR camera. To get a 24mm focal length equivalent you’ll need to use an 15-18mm full size lens to get you close to 24mm.

Using a 50mm full sized lens on an APS sensor camera works out to an 80mm equivalent, which actually gets you in the range of a nice portrait lens. A good fast 50mm lens is a great first lens to have in your photographic arsenal no matter what size sensor you have in your DSLR.

And if getting really close to the action is your thing, it works out even better with telephoto lenses. A 200mm full frame lens becomes a 320mm lens! Talk about getting close to your distant subject.

When you do upgrade to a full frame sensor DSLR camera, you can continue using all of your full frame lenses, although focal lengths will return to their standard focal lengths. 24mm is 24mm, 50mm is 50mm and so on. No more math!

Using a Higher ISO Setting in Low Light:

One thing I haven’t mentioned in this 102 level class is the ISO setting on your camera. I talk about this more in the 101 class. You can certainly increase the sensitivity of your sensor electronically much the same way we used to use faster film in lower light situations back in the film days to help get the required amount of light to your sensor, especially when you are shooting anything with action and you have to increase your shutter speed to 1/250th or 1/500th of a second to freeze the motion.

But there is a compromise here as well. A faster ISO setting (conveyed in higher numbers – ISO 100 being a lower light sensitivity setting and 800 or 1250 ISO being a much higher light sensitivity setting) are going to result in more grain or noise in your image. The newer DSLR cameras are not as noisy in the higher ISO settings as they were as recently as four or five years ago, but it’s still something to be aware of as you’re selecting the proper aperture, shutter speeds and ISO settings to make a technically good image. A noisy photograph will look slightly less sharp and clean.

In Conclusion, How to Get the Most For Your Money:

Everything is a little bit of a compromise unless you have a lot of money to spend, which most emerging photographers do not have. Photography is a very expensive undertaking, but there are choices you can make to keep it within your budget by taking into account the things I have discussed here.

Billy in Santa Fe, New Mexico (photo by Sarah Cramer) ©2008

Billy in Santa Fe, New Mexico (photo by Sarah Cramer) ©2008


20 years ago, I started out buying used equipment to help keep my costs down. When camera companies upgrade their camera lines, a lot of photographers are looking to sell their old digital camera bodies. Back in the days of film, photographers didn’t unload old cameras nearly as much, hanging onto those old bodies for years because the technology didn’t change as rapidly and they worked just as well even if they were 10 years old. So being in the market for a used digital camera is actually easier than it used to be. Good used lenses are harder to come by however, because, like I said, a good lens usually dramatically outlives its digital camera body counterpart in usefulness, so there are fewer of them floating around out there.

If you’re still not sure what lenses you want to buy, a great way to try out lots of different focal lengths is to rent a lens or two for a week. Doing a Google search for Canon lens rental, for instance, will bring up a list of companies that will ship you a lens for a few days or longer for less than $50. You’ll find many different kinds of lenses to choose from. The more expensive lenses are more expensive to rent, but getting to use a $1500 fast zoom lens for a few days for around $100 is a great way to figure out what you may want to buy without having to starve yourself for a month or two. Trying before you buy is a great idea. It takes some of the pressure and guesswork out of what first lenses to buy when you’re on a tight budget.

Hopefully this information helps a bit. It may seem a bit complicated at first, but photography, like any other skill set, takes a commitment to learning to fully understand and master. It’s worth it. A great photograph can last a lifetime or longer!

Up next… Class 103 – Finding Your Style.

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